1. Field of the Invention
The present disclosure relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a method of manufacturing the same.
2. Discussion of the Related Art
Until recently, display devices have typically used cathode-ray tubes (CRTs). Presently, many efforts and studies are being made to develop various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays, and electro-luminescence displays (ELDs), as a substitute for CRTs. Of these flat panel displays, LCD devices have many advantages, such as high resolution, light weight, thin profile, compact size, and low voltage power supply requirements.
In general, an LCD device includes two substrates that are spaced apart and face each other with a liquid crystal material interposed between the two substrates. The two substrates include electrodes that face each other such that a voltage applied between the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field into the direction of the induced electric field, thereby changing the light transmissivity of the LCD device. Thus, the LCD device displays images by varying the intensity of the induced electric field.
FIG. 1 is a cross-sectional view illustrating an LCD device according to the related art.
Referring to FIG. 1, the LCD device includes a liquid crystal panel 10 including an array substrate, a color filter substrate and a liquid crystal layer 50 therebetween, and a backlight below the liquid crystal panel 10.
The array substrate 10 includes a gate line (not shown) and a data line 4 on a first substrate 1 that cross each other to define a pixel region P. A thin film transistor Tr is formed in a switching region TrA near the crossing portion of the gate line and the data line 4. A pixel electrode 24 is formed in a display region AA to substantially display images and connected to the thin film transistor Tr.
The thin film transistor Tr includes a gate electrode 11, a gate insulating layer 13, a semiconductor layer 15, and source and drain electrodes 17 and 19.
A passivation layer 21 is formed on the first substrate 1 having the thin film transistor Tr, and the pixel electrode 24 is formed on the passivation layer 21 and connected to the drain electrode 19.
The color filter substrate includes a black matrix 32 made of black resin on a second substrate 2. The black matrix 32 shields the non-display elements such as the gate line, the data line 4 and the thin film transistor and exposes the pixel electrode 24.
Red (R), green (G) and blue color filters 34 are formed corresponding to respective openings of the black matrix 32. A common electrode 36 is formed on the color filter 34 and the black matrix 32.
In the LCD device, abnormal distribution of electric field occurs around step portions made due to electrodes and lines, and this causes liquid crystal molecules to be operated abnormally. Accordingly, light leakage occurs around the step portions.
The black matrix 32 is located corresponding to regions, where the abnormally-operated liquid crystal molecules exist, for example, the gate line and the data line 4 to prevent the light leakage.
Further, the black matrix 32 extends such that the black matrix 32 covers portions of the pixel electrodes 24 at both sides of the data line 4 as well as the data line 4.
For example, the black matrix 32 is configured to have a VAC (viewing angle crosstalk) margin D to prevent the VAC defect which is that light leakage is seen according to viewing angles of a viewer through a separate region between the data line 4 and the pixel electrode 24. However, in this case, aperture ratio is reduced.
To resolve the problems, a structure shown in FIG. 2 is suggested. Referring to FIG. 2, a common line 6 overlapping a pixel electrode to form a storage capacitor is formed below the data line 4. This structure functions to block light leakage through the separate region between the data line 4 and the pixel electrode 24, and thus the VAC defect is prevented. In this case, the black matrix 32 does not need the VAC margin (D of FIG. 1), and thus aperture ratio is improved.
However, in the device of FIG. 2, since the common line 6 is below the data line 4, the common line 6 and the data line 4 create a parasitic capacitance with the gate insulating layer 13 as a dielectric. The parasitic capacitance functions as a resistor and causes signal delay and increase of current consumption. Accordingly, reliability is reduced, and disconnection of the data line is caused.